Yanmar 4LHA-HTP User Manual

Chapter 3 Fuel Injection Equipment
5. Automatic Advancing Timer
i 4LHA Series
5. Automatic Advancing Timer
5-1 Timer construction
The faster the engine speed, the larger the crank angle
is during ignition delay. This results in a delay in
ignition time and thus a decrease in engine output.
When an engine is used from low to high speed, the
injection timing must be changed according to engine
speed to maintain it at the optimum timing.
The automatic timer uses centrifugal force to auto-
matically adjust injection timing.
Model
Identification code
Advanced angle
See separate service data
Timer assy.
Circlip-
Spring retainer—©
Spring guide
Timer hub Shims
Retainer
Flyweight
Identification code
5-2 Function and characteristics of timer
The flyweights are pressed against the center of the
flyweight by the springs. As speed increases, the
centrifugal force of the two flyweights increases,
compresses the timer springs, and the relative position
of the timer gear and hub changes according to the
function of the retainer guide groove of the weight
and the weight guide of the timer gear, changing the
injection timing. Accordingly, as the spring is com-
pressed (according to the rise in speed advancing the
timing), the advancing angle remains proportional
to speed.
Engine speed
The advancing characteristics can be changed by chang-
ing the profile of the retainer guide groove of the
weight and the spring constant and setting force of
the spring
3-2-38

Yanmar 4LHA-HTP Specifications

General

Brand	Yanmar
Model	4LHA-HTP
Category	Engine
Language	English